Stent Implantation Versus Balloon Dilation for Acute Anterior Circulation Tandem Occlusion

1. To evaluate whether stent implantation on the ipsilateral extracranial segment, after intracranial thrombectomy successful recanalization compared with balloon angioplasty (eTICI≥2b\_50) for acute anterior circulation tandem lesions within 24h of onset, can improve neurological functional outcomes(mRS≤2). 2. To evaluate whether stent implantation on the ipsilateral extracranial segment, after intracranial thrombectomy successful recanalization compared with balloon angioplasty (eTICI≥2b\_50) for acute anterior circulation tandem lesions within 24h of onset, can increase the risk of symptomatic intracranial hemorrhage.